Air cleaner



May 7, 1935. w. w. LOWTHER 2,000,706

AIR CLEANER Filed Dec. 15, 1933 5 Sheets-Sheet 1 Fig. i

13 16 7 /NVNTOR Ward-0 I)! Lon THU? BY #15 ATTaRNEYs M 7, 1935. w. w. LOWTHER 2,000,706

AIR CLEANER I Filed Dec. 15, 1935 0 s Sheets-Sheet 2 A 7 Fig. 3 5

I? j B42 '15 9 h 1/ 13 a 8 8 1 fiwnvrae VV/LFEED W Lon 7M5? BY Ms ATTORNEYS May 7, 1935. w. w. LOWTHER AIR CLEANER Filed Dec. 15, 1933 3 Sheets-Sheet 3 2w F. my NT WWW ar mm M. m

Patented May 7, 1935 I I UNITED. STATES PATENT OFFICE AIR CLEANER Wilfred w. Lowther, Minneapolis, as-

signor to Donaldson Company, Inc., St. Paul, Minn., a corporation of Minnesota Application December 15, 1933, Serial No. 702,482

14 Claims. (01. 183-15) -My present invention relates to air cleaners tube 6 and is provided with an air outlet I2 and has for its object to improve the same in adapted to be coupled to the carburetor of an various important particulars, whereby efficiency internal combustion engine. An oil distributing of the same is increased and rendered dependable dust-intercepting screen A is placed in the an- 5 and reliable, regardless of the varying flow of air nular space between the casing and air intake 5 through the cleaner. The air cleaner is especialtube and extends from the bottom of the air ly adapted for use in connection with internal chamber ll down to a point near but above the combustion engines. The most diflicult problem lower end of the air intake tube. This screen in the cleaning of air delivered to internal comis preferably made from quite finely woven wire bustion engines is encountered when air cleanand may take various forms, for example, it may 10 ers are used in connection with engines of 0011- be such as that disclosed in the application of siderable size, having a small number of cyl- William H. Schulz Serial No. 616,860, filed June inders, for such engines produce an uneven or 14, 1932, and entitled Air cleaner. For the pulsating flow of air, which in an air cleaner purpose of this case, attention is simply furemploying oil, tend to produce an uneven and ther called to the fact that the screen, as shown, 15 inefficient dust-collecting and air cleaning acis made up of annular woven wire members, tion. Also, at high engine speeds, the dustthe surfaces of which are inclined in such a collecting and air-cleaning action tends to beway that the oil intercepted will run down over come less eflicient. and form films of oil over the openings of said My invention overcomes the above objections screens and through which oil films the air will 20 and generally increases the efficiency and rebe caused to pass, and by which oil films the dust liability and dependability of air cleaners wherewill be intercepted and returned to the oil well. in oil or other liquid dust-absorbing materials As a highly important feature, an annular or are employed, all as will hereinafter more fully endless baflle I3 is placed around the lower end appear. of the air tube 5. This bafile is spaced both from 25 The invention is illustrated in the accomthe air intake tube and from the casing and expanying drawings, wherein like characters intends both above and below the lower end of dicate like parts throughout the several views. said tube. An annular air passage I4 is thus Referring to the drawings: formed between the lower delivery end of the air Fig, 1 is a vertical axial section illustrating tube and the said baflle. To restrict the cross- 30 one form of the improved air cleaner; section of this air passage at the extreme lower Fig. 2 is a horizontal section taken on the line end of the air tube, the latter is shown as pro- 2-2 of Fig. 1; vided with an outstanding annular deflecting Fig. 3 is a horizontal section taken on the line flange I5, the important purpose of which will 3-3 of Fig. 1; and more fully appear in the description of the op- 35 Fig. 4 is an axial section showing the lower eration. The baflie l3 may be supported or held portion of an air cleaner of modified form in rein position by any suitable means as, for example, spect to one of the important elements. by small angle brackets I6 riveted thereto and Referring first to the construction illustrated to the bottom of the oil well I. It will be noted 40 in Figs. 1, 2 and 3, the air cleaner involves a that the upper edge of the baiile I3 extends to 40 casing or outer shell 5, preferably in the form and practically terminates against the bottom or of an upright cylinder, the lower end of which lowermost portion of the screen A. is primarily open. An axial air intake tube 6 Fig. 4 illustrates a modified form of the annuextends downward through the casing 5, An lar or endless baflle structure and wherein the oil well I in the form of a large cup is telescoped same is made up of a plurality of concentrically 45 onto the lower end of easing 5 and, of course, spaced annular baffles II, I8 and I9. In this arnormally closes the lower end of said casing. rangement, the several baflies are preferably ter- This oil well I is made readily detachable and is miriated at about the same upper level, but at secured to the casing by suitable means, such their lower edges, those that are progressively furas upwardly spring-pressed hook bolts 8 that ther from the air intake tube project progressively 50 work through lugs 9 on the exterior of the casfarther downward into the oil well I. As shown, ing 5 and engage out-turned lugs In on the exthe outer bafile I9 is supported from the bottom terior of the upper edge of said oil well. At of the oil well I by brackets 20, and the several the upper end of the casing is an air chamber ll baflles are tied together and spaced by any suitthat surrounds the upper portion of air intake able means such as interposed spacing lugs.

Bailles 11, I8 and I9 are spaced apart and rigidly connected and supported by spacing lugs "a.

Operation of structure of Figs."1, 2 and 3 Under suction produced by the engine through the carburetor, a more or less rapid circulation of air will be drawn to the carburetor through the air intake tube, into the chamber formed within the annular baiile l3, thence upward through the screensfinto the air chamber II and out through the air discharge tube or passage I2. Air discharged from the lower end of the air tube 6 will be dashed against the oil and the oil in the said chamber will be depressed, and some thereof will be displaced into the outer portions of the oil well surrounding the annular baflle l3, thereby raising the oil level above the outer portions of the oil well and forming an annular head of oil that projects into the annular screen-containing chamber of the casing. Of course, the amount of the oil in the chamber formed by the bafile I3 is depressed and the height of the resultant annular head of oil will depend largely upon and vary with the velocity of the air passing through the cleaner. As the air makes its initial contact with and is turned upward by the oil, the surface of the oil will be dashed into a spray or form, which will be carried upward by the air into the screen chamber and through the screen openings to a greater or less height, dependent upon the force or velocity of the air, and under relatively constant engine speed, oil carried out of the chamber formed by the annular baflle l3, will be continually replaced by oil flowing in under the annular baflie l3 from the outer portions of the oil well, below the head of oil.

This continued replacement of oil from the chamber formed by the baflle I 3 is obviously the result of a higher level of oil being maintained outside of the baflle than within the same, during the operation of the cleaner. Oil carried upward into the screen chamber will be caught by the screen elements and caused to run downward over the declined surfaces thereof and form films over the openings therein, through which openings air and whatever dust remains therein must pass. In this manner, all dust remaining in the air after the dust-laden air is turned upward against the surface of the oil, is intercepted by oil at some point during its travel through the screen chamber and will be returned to the well with downwardly flowing oil, since, as previously indicated, there is a continuous return flow of oil from the outer portions of the oil well into and out under baflle I 3. It will be obvious that some of the oil caught by the screen elements will run down the outward declines thereof to the outer portions of the casing and even be deposited in the annular head of oil and some of the oil caught by the screen elements will run down the inward declines thereof toward intake tube 6. Oil from the head of oil maintained above and outward of the baffle I3 will tend to and, in fact, will overflow the upper edge of battle I3 and upon entering the air stream at this point of high air velocity, will be again whipped up by the air and returned to the screen chamber in an atomized form. Since the increasedsuctional area of the air passage is greatly restricted immediately above the baflle l3, the air rapidly expands at this point and, of course, this expanding of the air will cause all oil suspended in the air stream above the baffle II to be finely broken up so as to produce the referred to atomization or breaking up of the oil.

In practice, I have found it highly desirable to produce a relatively rapid movement of the air close to the point where the air makes its initial contact with the oil, to wit: at the place where the air makes its upward turn against the oil and between the lower end of the air intake tube and the baille l3. This passage I4 is restricted by the annular flange l5, which performs a secondary highly important function, to wit: it forms an eddy space adjacent to the lower outer surface of the air tube along which the oil is free to run downward, as indicated in Fig. 1. This oil, when it reaches the flange l5, will be deflected outward into the rapidly travelling upwardly moving air and will be again carried up with the air. The flange l5 not only aids in returning collected oil to the air stream at the point where it makes its upward turn, but due to the increased restriction of air passage afforded thereby, increases the velocity of the air and therefore further aids in breaking up all air suspended oil coming in the vicinity of the upper edge of the baflle 13.

The vertical extent of the screen chamber is such that oil will not be carried upward through all of the screen elements, even by intense pulsations produced by large two-cylinder internal combustion engines. Of course, also the altitude to which the oil will be carried will be dependent upon engine speed, regardless of number of cylinders and variation in intensity of pulsations. Obviously, during the normal operation of the cleaner, under relatively constant air velocity, the only return of oil to the oil Well is outside of the annular baflle.

This chamber-forming baifle l3, it is important to note, is so completely open at its bottom that the oil, when at rest, will quickly seek its level both within and outside of said batlle. Hence, under varying intensity in the flow of air, the oil in the chamber within the baffle will be depressed variably but under no condition will the oil be entirely forced from the interior of said baiile, but on the contrary, there will be such free sup ply of oil that the displacement of oil will be due entirely to the pressure from the air flowing against the oil from the discharge end of the air tube 6. The batlle l3 limits the upward flow of the oil to the screens, to the annular space between the same and the lower end of the air tube and causes the return of oil to take place chiefly through the annular space outside of said battle. The normal level of the oil, to wit: the level thereof under static conditions is indicated by the broken line marked y-y on Fig. 1, which level is well above the lower end of the air intake tube. It is also important to note that the battle l3 extends up to or approximately to the normal oil level 11 and that the screens A are brought down to or approximately to said level. These relative arrangements may be varied but, in practice, it has been found that the best results have been obtained by substantially the relative arrangement just noted and illustrated in the drawings. With the said preferred arrangement, the screens are caused to commence their action as soon as the dust-laden air passes above the said baffle ll. Of course, the large amount of the heavier dust or foreign materials in the air will be precipitated against and directly taken up by the oil where it makes its turn and initial contact with the oil against the oil surface on its way up to the annular passage ll. As the air passes upward from the said e M to the screens, it will, as previously noted, be subjected to a violent cummingling with the oil flowing downward against the The operation of the structure illustrated in Fig. 4 is in most respects like or substantially like that of the structure illustrated in Figs. 1, 2 and 3. This structure, however, is especially intended for use in connection with engines wherein there is a very great range in the velocity of the air and hence in the pressure thereof produced in the surface of the oil. with the arrangement of the baflles ll, I8 and [9, when the oil is depressed only to a level indicated by the dotted line :r.'c, the flow of oil will be entirely upward between the flange I andthe inner baflle II; when the oil is further depressed as indicated by dotted lines marked x -:c the flow of oil will be not only upward through the space between flange l5 and inner batlle I1, but will also be upward between the said baflles l1 and I8; and when.

the oil is further depressed say to the level indicated by the dotted line 32 -4 the flow of oil will be upward through the passage between flange l5 and battle I'I, upward between the battles I1 and I8, and upward between the baffles l8 and I9. This arrangement of bailles provides a sort of an oil well or chamber in whichthe effective diameter thereof increases substantially in proportion to the increased depression of the oil.

Otherwise stated, in a; cleaner incorporating these bailles, the eifective capacity of the cleaner with regard to air passage restriction, increases and decreases substantially in proportion to the velocity of air passed therethrough with the result that the cleaner renders substantially the same degree of efficiency over a wide range of engine speeds and consequent variations in air velocity.

The overall dimensions of either form of the cleaner herein described, when used in connection with an internal combustion engine of given horse-power, can be relatively small as compared with most other types of cleaners employing a fluid, and this is a highly important feature,

since the space allotted for air cleaner equipment is often very limited and many times results in the use of under-sized equipment.

What I claim is:

1. An air cleaner comprising a casing having an oil well in its bottom and an air outlet in its upper portion, an air intake tube leading axially downward through said casing, a screen in the space within said casing surrounding said air intake tube, and an annular baille in said oil well spaced from the walls and bottom of said well and from the lower end of said air intake tube, said annular bailie afiording a chamber within said oil well that is unobstructed below the intake tube and, at its bottom has free and unobstructed communication with the bottom of said well, said annular baflle being extended to a point considerably above the lower end of said air tube and said screen being extended downward substantially to the upper edge of said annular bailie.

2. The structure defined in claim 1 in which the normal or static oil level in said well is approximately at the lower portion of said screen and the upper edge of said annular baflle.

3. An air cleaner comprising a casing having an oil well in its bottom and an air outlet in its upper portion, an air intake tube leading axially downward through said casing, a screen in the space within said casing surrounding said air intake tube, and an annular bame in said oil. well spaced from the walls and bottom of said well and from the lower end of said air intake tube, said annular baflle affording a chamber within said oil well which, at its bottom, has free and unobstructed communication with the bottom of said well, said air tube at its lower end having an outstanding annular flange affording a restricted annular passage between the same and said battle.

4. The structure defined in claim 1 in which the normal or-static oil level in said well is approximately at the lower portion of said screen and the upper edge of said annular baflle, said air inlet tube at its lower end having an out-' standing annular flange that restricts the annular air passage between the same and the surrounding baille and cuts off direct upward flow of air adjacent to the lower portion of said air tube.

5. The structure defined in claim 1 in which the oil well at the bottom of said casing is detachable therefrom, is telescoped onto said casing, and extends well above the normal or static oil level of said well, said annular baille being supported by and removable with said oil well.

6. An air cleaner comprising a casing having an oilwell at its bottom and an air outlet at its upper portion, an air intake tube leading axially downward through said casingwith its lower end positioned to deliver air into said oil well, and an annular baffle spaced from said air tube and from the bottom and sides of said oil well and extended to a point above the lower end of said air tube and affording a chamber within said oil well which, at its bottom, has free communication with the bottom of said well, said annular baflle being made up of a plurality of concentrically spaced rings, the rings that are progressively farther from the axis of the casing being extended progressively deeper into said well.

7. An air cleaner comprising a casing having an oil well at its bottom and an air outlet at its upper portion, an air intake tube leading axially downward through said casing with its lower end positioned to deliver aifinto said oil well, and an annular baflle spaced from said air tube and from the bottom and sides of said oil well and extended to a point above the lower end of the air tube and aflording a chamber within said oil well which, at its bottom, has free communication wth the bottom of said well, said annular baflle being made up of a plurality of concentrically spaced rings, the rings that are progressively farther from the axis of the casing being extended progressively deeper into said well, the static or normal oil level of the well being above the lower end of said air tube and said bathe-forming rings at their upper edges being located approximately at said oil level.

8. The structure defined in claim '7 in which said air tube at its lower end and below the upper edges of said ring-forming bailles is provided with an outstanding annular flange that restricts the air passage between said air tube and the innermost ring.

9. An air cleaner comprising a casing having an oil well in its bottom and an air outlet in its upper portion, an air intake tube leading axially downward through said casing, and an annular bafiie in said oil well spaced from the walls and bottom of said well and from the lower end of said air intake tube, said annular baflle affording a chamber within said oil well that is unobstructed below the intake tube and, at its bottom, has free and unobstructed communication with the bottom of said well, said annular bailie being extended to a point above the lower end of the intake tube and being open at its top for communication with the interior of the easing above the oil well.

10. An air cleaner comprising a casing having an oil well in its bottom and an air outlet in its upper portion, an air intake tube leading axially downward through said casing, and an annular baiiie in said oil well spaced from the walls and bottom of said well and from the lower end of said air intake tuba-said annular baiiie ailording a chamber within said oil well that is unobstructed below the intake tube and, at its bottom, has free and unobstructed communication with the bottom of said well, said oil well at the bottom of said casing being detachable therefrom, being telescoped onto said casing, and extended well above the normal or static oil level in said well, the said annular baille being secured to and removable with said oil well.

- 11. An air cleaner comprising a casing having an oil well in its bottom and an air outlet in its upper portion, an air intake tube leading axially downward through said casing, and an annular baille in said oil well spaced from the walls and bottom of said well and from the lower end of said air intake tube, said annular baileafl'ording a chamber within said oil well that is unobstructed below the intake tube and, at its bottom, has free and unobstructed communication with the bottom of said well, said oil well at the bottom 01' said casing being detachable therefrom. and being telescoped onto said casing.

12. An air cleaner comprising a casing having an 'oil well in its bottom and an air outlet in its upper portion, an air intake tube leading axially downward through said casing, a screen in the space within said casing surrounding said air intake tube, and an annular bathe in said oil well spaced from the walls and bottom of said well and from the lower end oi said air intake tube, said annular baiile affording a chamber within said oil well, which, at its bottom, has free and unobstructed communication with the bottom of said well.

13. An air cleaner comprising a casing provided with an oil well in its lower portion and having an air inlet and an air outlet, dust and oil-intercepting means located in said casing between said oil well and air outlet, and a substantially annular baflie located in said oil well and affording a chamber within said well, located between said air inlet'and intercepting means and past the upper edge of which baiile the dustladen air will move on its way from said air inlet to said intercepting means, said inlet, outlet, oil well, baiiie and intercepting means being in concentric arrangement.

14. The structure defined in claim 13 in which 

